Cut away the tops and bottoms of the rhubarb stalks, rinse and cut them into 2-3 cm slices.
Roll the rhubarb pieces in sugar, vanilla, lemon zest and juice. Place them in an oven-proof dish and bake at 150°C for 20-25 minutes.
Cool off the baked rhubarb until it is ready for trifli. Use the juice in which the rhubarb was turned in the friskost cream.